Magnesium alloy material and method for manufacturing the same

Abstract

The present invention provides a magnesium alloy material excellent in mechanical properties without using specific manufacturing facilities and processes and a method of manufacturing the same. The magnesium alloy material is an Mg—Zn—RE alloy containing, as an essential component, Zn and at least one of Gd, Tb, and Tm as RE, and of the rest including Mg and unavoidable impurities, and has stacking faults of a thickened two-atomic layer of Zn and RE in the alloy structure of the Mg—Zn—RE alloy. A method of manufacturing a magnesium alloy material involves a casting step, a solution treatment step, and a heat treatment step and the heat treatment step is carried out in a condition satisfying −14.58 [ln(x)]+532.32<y<−54.164 [ln(x)]+674.05 and 0<x≦2, wherein y denotes the heat treatment temperature (K) and x denotes the heat treatment time (h).

Description

TECHNICAL FIELD[0001]The present invention relates to a magnesium alloy material and a method for manufacturing the same and particularly to a magnesium alloy material having high mechanical strength and a method for manufacturing the same.BACKGROUND ART[0002]In general, magnesium alloy materials have the lowest density among alloys in practical use, lightweight and high strength and accordingly have been promoted for applications to chassis of electric products, wheels of automobiles, underbody parts, peripheral parts for engines, and the like.[0003]In particular, with respect to parts for uses relevant to automobiles, since high mechanical characteristics are required, as magnesium alloy materials containing an element such as Gd, Zn and the like, materials with specified configurations have been manufactured by a single roll process and a rapid solidification process (e.g. Patent Document 1, Patent Document 2, and Non-Patent Document 1).[0004]However, in specified manufacturing m...

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Benefits of technology

[0024]A magnesium alloy material and its manufacturing method according to the invention have the following excellent effects.

[0025]Since the magnesium alloy material contains stacking faults of the thickened two-atomic layer of Zn and RE in the alloy structure (mother phase), the tensile strength, elongation, and 0.2% proof strength at a prescribed elongation ratio can remarkably be improved as compared with those having a long period stacking ordered structure. Further, if extrusion (plasticity) processing is carried out, since fine crystal grains are generated in the alloy structure, mechanical characteristics too high to be achieved generally can be obtained. Therefore, the magnesium alloy material can be used also, for example, automotive parts, particularly, parts such as pistons or the like which are required to have very severe mechanical characteristics.

[0026]Since the method for manufacturing the magnesium alloy material involves heat treatment in condition of the prescribed range after the solution treatment, the magnesium alloy material contains the stacking faults of the thickened two-atomic layer of Zn and RE in the alloy structure (mother phase). Therefore, the magnesium alloy material provided with the tensile strength, elongation, and 0.2% proof strength at a prescribed elongation ratio improved as compared with those of a conventional material can be produced efficiently by common manufacturing facilities or processes.

[0027]Further, in the method for manufacturing the magnesium alloy material, the heat treatment temperature and the heat treatment time are adjusted in a condition satisfying −14.58 [ln(x)]+532.32<y<−54.164 [ln(x)]+674.05 and 0<x≦2, wherein y denotes the heat treatment temperature (K) and x denotes the heat treatment time (h), so that the magnesium alloy material provided with improved tensile strength, elongation, and 0.2% proof strength at a prescribed elongation ratio in a widened range (as compared with those of a magnesium alloy material having the long period stacking ordered structure) can be manufactured.

Problems solved by technology

However, in specified manufacturing methods, although providing the above-mentioned magnesium alloy materials with high mechanical characteristics, there are problems that special facilities are required, the productivity is low, and further applicable parts are limited.

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